Three-dimensional hierarchical mesoporous flower-like TiO2@graphdiyne with superior electrochemical performances for lithium-ion batteries

Abstract

Three-dimensional hierarchical flower-like TiO₂@graphdiyne is prepared via a solvothermal process, and the structural properties and electrochemical performances are systematically investigated. The obtained results show that TiO₂@graphdiyne delivers a high reversible capacity of 432.4 mA h g⁻¹ after 300 cycles at a current density of 1 A g⁻¹, about 3 times that (139.7 mA h g⁻¹) of pristine TiO₂. The high reversible capacities, excellent rate capability and cycle stability of TiO₂@graphdiyne might be attributed to the hierarchical mesoporosity of graphdiyne with butadiyne linkages, which could not only provide innumerable interconnected active sites for lithium storage but also facilitate fast Li-ion diffusion. The built-in electric field derived from the difference in work function between TiO₂ and graphdiyne could facilitate electron-transfer and Li-ion migration across heterojunction interfaces. Moreover, electron percolation and a local built-in electric field induced by oxygen vacancies in the TiO₂ matrix could also enhance the kinetics of Li-ion insertion/deinsertion.